The objective of the proposed research is to explore the feasibility of detecting antigens in expired human breath. The 30kDa native mycobacterial antigen has been selected as a model system because mycobacteria are not part of the normal flora of the respiratory tract, so clearcut positive and negative values should be obtained by comparing tuberculosis patients with controls. Detection of antigen vaporized by a nebulizer will represent a design step to adapt the technology to gas phase detection, calibrate the sensitivity and test approaches to allow operation under conditions of high humidity. Clinical testing will involve patients with tuberculosis and controls, comparing various devices to collect, and channel breath expired by coughing, talking or other respiratory maneuvers. The proposed research is a high risk attempt to develop a new technology. No historical base exists for the proposed technological approach and sensitivities at the state of the art will be required. Nonetheless, the resources and expertise of an experienced, multidisciplinary team of collaborators are being brought to bear on the problem, and great potential exists for a new method for rapid, extremely sensitive and non-invasive monitoring of the pulmonary compartment.